| coupled reaction | Two chemical reactions that share a common intermediate (for example, the productof the first reaction is a reactant in the second) and therefore havesome kind of energy exchange between them. (09 Oct 1997) |
|---|---|
| Porter-Silber reaction | The basis of the 17-hydroxycorticosteroid test; C-21 adrenocorticosteroids, which contain a dihydroxyacetone group at carbons 19, 20, and 21, react with phenylhydrazine. (05 Mar 2000) |
| Haber-Weiss reaction | The reaction of superoxide (O2-- with hydrogen peroxide to produce molecular oxygen (O2), hydroxide radical (OH-), and OH-; often, iron catalyzed; a source of oxidative stress in blood cells and various tissues. (05 Mar 2000) |
| haemoclastic reaction | Haemolysis as observed in the laking of the blood. (05 Mar 2000) |
| cutaneous graft versus host reaction | An acute erythematous maculopapular reaction with bulla formation in the most severe cases; chronic changes may resemble lichen planus or scleroderma. (05 Mar 2000) |
| cutaneous reaction | The inflammatory reaction in the case of a skin test in a sensitive (allergic) subject. Synonym: cutaneous reaction. Origin: L. Cutis, skin, + reaction (05 Mar 2000) |
| Prausnitz-Kustner reaction | A test for the presence of immediate hypersensitivity in humans; test serum from an atopic individual is injected intradermally into a normal subject; the normal subject is challenged 24-48 hours later with the antigen suspected of causing the immediate hypersensitivity reaction in the atopic individual. Synonym: P-K test. (05 Mar 2000) |
| precipitin reaction | See: precipitin, precipitin test. (05 Mar 2000) |
| harlequin reaction | Sudden blanching of the lower half of the body of an infant lying on its side, leaving the remaining half of the body the normal pink colour. (05 Mar 2000) |
| cytotoxic reaction | An immunologic (allergic) reaction in which noncytotropic IgG or IgM antibody combines with specific antigen on cell surfaces; the resulting complex initiates the activation of complement which causes cell lysis or other damage, or which, in the absence of complement, may lead to phagocytosis or may enhance T lymphocyte involvement. (05 Mar 2000) |
| primary reaction | <dermatology> The cutaneous and sometimes systemic reactions associated with vaccination with smallpox vaccine. (18 Nov 1997) |
| Sakaguchi reaction | Guanidines in alkaline solution develop an intense red colour when treated with alpha-naphthol and sodium hypochlorite; a qualitative test for arginine, free or in a protein. (05 Mar 2000) |
| Henle's reaction | Dark brown staining of the medullary cells of the adrenal bodies when treated with the salts of chromium, the cortical cells remaining unstained. (05 Mar 2000) |
| Schardinger reaction | The reduction of methylene blue to methylene white by formaldehyde is rapidly catalyzed by fresh milk but not by boiled milk, the catalyzing agent being xanthine oxidase (Schardinger's enzyme); an example of oxidation in the absence of O2 with an organic hydrogen acceptor (the dye). (05 Mar 2000) |
| Herxheimer's reaction | An inflammatory reaction in syphilitic tissues (skin, mucous membrane, nervous system, or viscera) induced in certain cases by specific treatment with Salvarsan, mercury, or antibiotics; believed to be due to a rapid release of treponemal antigen with an associated allergic reaction in the patient. Synonym: Jarisch-Herxheimer reaction. (05 Mar 2000) |